This invention relates to powered devices for applying torsional force to fasteners e.g., turnbuckles and other objects and, more particularly, the invention relates to an improved retaining and braking apparatus for use in such a powered device.
It is well-known to use a turnbuckle affixed to a chain or cable as a means for increasing the tension on the chain or cable. Two common applications of such chain, cable and turnbuckle arrangements are in guy wires for providing stability to radio antennas or other towers and in lashing down cargo aboard ocean-going vessels. The conventional method for turning the turnbuckle in order to increase the tension on the chain or cable attached thereto is to insert a rod through the turnbuckle, then apply force on the rod to rotate the turnbuckle, thereby increasing the tension on the chain or cable. Such manual procedures for tightening turnbuckles make the task of tightening the turnbuckle tedious, time-consuming and physically tiring. The inefficiency of manual tightening is a special problem on ocean-going vessels since one of the important factors in determining whether such vessels are profitable is the amount of turnaround time in unloading and reloading a vessel once it reaches port. The time-consuming job of lashing down cargo by manually tightening the turnbuckles attached to the lashing chains and cables greatly increases the amount of in-port time for any cargo vessel.
Powered wrenches or other devices for applying a torsional or rotational force to a fastener or other object are known in the prior art. An example of such a device is in U.S. Pat. No. 3,535,960 to Borries, issued Oct. 27, 1970. The use of such devices for turning turnbuckles has been limited by several factors. One such factor is in the size of the powered devices presently manufactured. The other is in the relatively high torsional force required to satisfactorily tighten a chain or cable such as in holding down cargo on an ocean-going ship which will be subjected to severe movement due to the waves encountered in the ocean crossing. In order to properly utilize a powered device to tighten the turnbuckle it is necessary to have positive assurance that the device will not slip off the turnbuckle during the tightening procedure. Slippage of the tool can be particularly hazardous during the high torque application encountered in tightening the turnbuckles of cargo lashings.
A further requirement of the use of any high torque, powered, wrench-like device in tightening turnbuckles is the necessity of providing some means by which the powered device can be placed on the turnbuckle or other fastener and removed therefrom. In the case of a nut or bolt head, the wrench can be placed easily over the top of the nut or bolt head and removed in a reverse manner. When dealing with a turnbuckle, however, the problem is aggravated by the fact that the turnbuckle is usually attached at both ends either to a long length of continuous chain or cable or to some stationary structural member so that it is impossible to slide the wrench onto the turnbuckle from either end. The wrench therefore must be applied to the turnbuckle directly from the side of the turnbuckle at a 90.degree. angle. Such an arrangement necessitates the placement of a slot in the head of the wrench or other device so that it can be slipped over the turnbuckle from the side. It is necessary that the slot in the head be properly aligned for placement of the device over the turnbuckle at the start of the operation and similarly aligned at the finish of the tightening operation so that the tool can be easily removed from the turnbuckle.
It is therefore an object of the present invention to provide a retainer mechanism for use with a powered tool for applying rotational force to a turnbuckle to prevent the turnbuckle from inadvertently becoming disengaged from the tool during tightening.
It is a further object of this invention to provide a retainer mechanism which is easily releasable by the operator of the powered tool while still maintaining a positive retaining capability and protection against accidental release.
It is another object of this invention to provide an apparatus for applying braking force to a turnbuckle tightening tool to permit the operator to stop the rotational motion of the apparatus at a point where the head of the tool is properly aligned for placement of the tool head on the turnbuckle or removal of the head from the turnbuckle.
It is an object of this invention to provide a retainer mechanism and brake apparatus which are integrated into a single operational unit.
It is a further object of this invention to provide a mechanism as described above that is simple to operate and maintain and relatively inexpensive to manufacture.